1. Field of the Invention
This invention relates to dispensing systems of the type which include a caulk gun for dispensing material from a disposable cartridge carried by the gun. The invention has particular application to a dispensing system of the type which dispenses a chemical composition, such as epoxy adhesive, comprising two reactive materials which are dispensed, respectively, from separate compartments of a cartridge and joined in a dispensing nozzle.
2. Description of the Prior Art
Many types of caulk gun dispensing systems are known for dispensing multi-material compositions from a multicompartment cartridge. Such dispensing systems are used in a number of different applications. One such application is for use by dental care personnel for dispensing adhesive materials, such as epoxy adhesives, for use in dental procedures.
A caulk gun of such dispensing systems typically has a body which carries a cartridge from which the materials are to be dispensed and also carries a plunger which is axially movable against pistons in the cartridge compartments for expelling materials from the cartridge compartments. The body is provided with two handles, one commonly fixed to the body and another pivotally movable and engageable with the plunger for moving the plunger axially forwardly in response to movement of the pivoting handle toward the fixed handle. Repeated manipulations of the pivoting handle are required to empty the cartridge and considerable force may be required to draw the handles together, depending upon the application.
In prior dispensing systems the pivoting handle is typically a straight handle which, in the normal rest configuration of the dispensing system, is angled away from the fixed handle. Thus, near the pivot the handles are close together and at their distal ends, the handles are a considerable distance apart. This results in uneven distribution of gripping force among the operator's fingers and may make it difficult for the operator to grasp the pivoting handle firmly enough with all fingers to apply the necessary closure force, particularly in the case of operators with relatively small hands. It is particularly difficult to move the pivoting handle its full distance to a position all the way against the fixed handle. This tends to reduce the distance that the plunger can be moved during any one handle closure operation and multiplies the number of handle closures which are required.
Gripping with the little finger can be alleviated by designing the dispensing system with a smaller angle between the handles in their normal rest configuration, but this also has the result of reducing the distance that the plunger can be axially moved during any one handle operation. It also tends to reduce the leverage available to the operator, since the fingers will be partially closed when they grip the handle and the human hand cannot exert as much initial closure force when it starts with the fingers in a partially closed position as it can when it starts with the fingers in a substantially extended position.
Furthermore, it has been found that the fixed handle of prior dispensing systems has not conformed well to the user's hand. This, together with the difficulties in manipulating the pivoting handle tends to result in fatigue and occasional hand injury as a result of prolonged use.